The objective of this project is to study the epidemiology of elevated blood pressure and hypertension during adolescence. The study subjects are drawn from a population for which extensive longitudinal data, collected prospectively, are available. Three samples of adolescents are being studied: (1) a random sample stratified by age, sex, and race; (2) a sample of adolescents whose mothers had toxemia of pregnancy; and (3) a sample of adolescents who had elevated blood pressure at age seven years. Antecedents variables include maternal and prenatal factors, complete postnatal medical histories, physical growth data, psychological test data, and detailed information about socioeconomic status. Current assessments are taking place at three annual intervals and include the collection of demographic information, recent medical history, blood pressure measurements, growth and maturation measures (height, weight, skinfold thicknesses, hand-wrist radiographs, and measures of steroid hormones), and psychological profiles. Our analyses will aim to clarify the relationship between elevations in blood pressure, antecedent variables, and current parameters of physical growth, body composition, mental health status, socioeconomic status, and sexual maturation.